If the system of equations
$x+\big(\sqrt{2}\sin\alpha\big)y+\big(\sqrt{2}\cos\alpha\big)z=0$
$x+(\cos\alpha)y+(\sin\alpha)z=0$
$x+(\sin\alpha)y-(\cos\alpha)z=0$
has a non-trivial solution, then $\alpha\in\left(0,\frac{\pi}{2}\right)$ is equal to:
Let $A=\begin{bmatrix}1\\1\\1\end{bmatrix}$ and
$B=\begin{bmatrix}
9^{2} & -10^{2} & 11^{2}\\
12^{2} & 13^{2} & -14^{2}\\
-15^{2} & 16^{2} & 17^{2}
\end{bmatrix}$,
then the value of $A'BA$ is:
Let the sum of the focal distances of the point $P(4,3)$ on the hyperbola $H:\ \dfrac{x^{2}}{a^{2}}-\dfrac{y^{2}}{b^{2}}=1$ be $8\sqrt{\dfrac{5}{3}}$. If for $H$, the length of the latus rectum is $l$ and the product of the focal distances of the point $P$ is $m$, then $9l^{2}+6m$ is equal to:
For the system of linear equations $\alpha x+y+z=1,\quad x+\alpha y+z=1,\quad x+y+\alpha z=\beta$, which one of the following statements is **NOT** correct?
The values of $\lambda$ and $\mu$ for which the system of linear equations
\[
\begin{aligned}
x + y + z &= 2,\\
x + 2y + 3z &= 5,\\
x + 3y + \lambda z &= \mu
\end{aligned}
\]
has infinitely many solutions are, respectively:
Let m and M be respectively the minimum and maximum values of
\[
\left|
\begin{array}{ccc}
\cos^{2}x & 1+\sin^{2}x & \sin 2x\\
1+\cos^{2}x & \sin^{2}x & \sin 2x\\
\cos^{2}x & \sin^{2}x & 1+\sin 2x
\end{array}
\right|.
\]
Then the ordered pair (m, M) is equal to :
$ \text{Let the minimum value } v_{0} \text{ of } v=\lvert z\rvert^{2}+\lvert z-3\rvert^{2}+\lvert z-6i\rvert^{2},\ z\in\mathbb{C} \text{ be attained at } z=z_{0}. \text{ Then } \lvert 2z_{0}^{2}-\overline{z_{0}}^{\,3}+3\rvert^{2}+v_{0}^{2} \text{ is equal to:} $
Let $A=\left[\begin{array}{ll}1 & 2 \\ 0 & 1\end{array}\right]$ and $B=I+\operatorname{adj}(A)+(\operatorname{adj} A)^2+\ldots+(\operatorname{adj} A)^{10}$.
Then, the sum of all the elements of the matrix
Let $A = [a_{ij}]_{2\times 2}$, where $a_{ij}\ne 0$ for all $i,j$ and $A^{2}=I$.
Let $a$ be the sum of all diagonal elements of $A$ and $b=\lvert A\rvert$ (i.e., $b=\det A$).
Then $3a^{2}+4b^{2}$ is equal to:
The number of values of $k$, for which the system of equations : $\matrix{
{\left( {k + 1} \right)x + 8y = 4k} \cr
{kx + \left( {k + 3} \right)y = 3k - 1} \cr
} $
Let $P$ be a square matrix such that $P^{2}=I-P$.
For $\alpha,\beta,\gamma,\delta\in\mathbb{N}$, if
$P^{\alpha}+P^{\beta}=\gamma I-29P$ and $P^{\alpha}-P^{\beta}=\delta I-13P$,
then $\alpha+\beta+\gamma-\delta$ is equal to:
Consider the matrix
$f(x)=\begin{bmatrix}
\cos x & -\sin x & 0\\
\sin x & \cos x & 0\\
0 & 0 & 1
\end{bmatrix}$.
Given below are two statements:
Statement I : $f(-x)$ is the inverse of the matrix $f(x)$.
Statement II : $f(x)f(y)=f(x+y)$.
In the light of the above statements, choose the correct answer:
Suppose $A$ is any $3\times 3$ non-singular matrix and $(A-3I)(A-5I)=0$ where $I=I_{3}$ and $O=O_{3}$. If $\alpha A+\beta A^{-1}=4I$, then $\alpha+\beta$ is equal to :
If the system of equations
$2x - y + z = 4$, $5x + \lambda y + 3z = 12$, $100x - 47y + \mu z = 212$
has infinitely many solutions, then $\mu - 2\lambda$ is equal to
Let $A = [a_{ij}]$ be a square matrix of order $2$ with entries either $0$ or $1$. Let $E$ be the event that $A$ is an invertible matrix. Then the probability $\mathrm{P}(E)$ is
Two fair dice are thrown. The numbers on them are taken as $\lambda$ and $\mu$, and a system of linear equations, x + y + z = 5, x + 2y + 3z = $\mu$ ,x + 3y + $\lambda$z = 1, is constructed. If p is the probability that the system has a unique solution and q is the probability that the system has no solution, then :
$ \text{Let } A \text{ and } B \text{ be any two } 3\times 3 \text{ symmetric and skew-symmetric matrices respectively. Then which of the following is NOT true?} $
Let A be a 3 $\times$ 3 matrix with det(A) = 4. Let Ri denote the ith row of A. If a matrix B is obtained by performing the operation R2 $ \to $ 2R2 + 5R3 on 2A, then det(B) is equal to :
Let $P=\left[\begin{array}{cc}\frac{\sqrt{3}}{2} & \frac{1}{2} \\ -\frac{1}{2} & \frac{\sqrt{3}}{2}\end{array}\right], A=\left[\begin{array}{ll}1 & 1 \\ 0 & 1\end{array}\right]$ and $Q=P A P^{T}$. If $P^{T} Q^{2007} P=\left[\begin{array}{ll}a & b \\ c & d\end{array}\right]$, then $2 a+b-3 c-4 d$ equal to :
Let $A$ be a $3 \times 3$ real matrix such that
$A\begin{pmatrix}1 \\ 1 \\ 0\end{pmatrix} = \begin{pmatrix}1 \\ 1 \\ 0\end{pmatrix}, \quad
A\begin{pmatrix}1 \\ 0 \\ 1\end{pmatrix} = \begin{pmatrix}-1 \\ 0 \\ 1\end{pmatrix}, \quad
A\begin{pmatrix}0 \\ 0 \\ 1\end{pmatrix} = \begin{pmatrix}1 \\ 1 \\ 2\end{pmatrix}.$
If $X = (x_1, x_2, x_3)^T$ and $I$ is an identity matrix of order $3$, then the system
$(A - 2I)X = \begin{pmatrix}4 \\ 1 \\ 1\end{pmatrix}$ has:
If for the matrix, $A = \left[ {\matrix{ 1 & { - \alpha } \cr \alpha & \beta \cr } } \right]$, $A{A^T} = {I_2}$, then the value of ${\alpha ^4} + {\beta ^4}$ is :
Let $A = \left[ {\matrix{ 0 & { - 2} \cr 2 & 0 \cr } } \right]$. If M and N are two matrices given by $M = \sum\limits_{k = 1}^{10} {{A^{2k}}} $ and $N = \sum\limits_{k = 1}^{10} {{A^{2k - 1}}} $ then MN2 is :
Let A be a symmetric matrix of order 2 with integer entries. If the sum of the diagonal elements of A2 is 1, then the possible number of such matrices is :
$A=\left[\begin{array}{cc}1 & 5 \\ \lambda & 10\end{array}\right], \mathrm{A}^{-1}=\alpha \mathrm{A}+\beta \mathrm{I}$ and $\alpha+\beta=-2$, then $4 \alpha^{2}+\beta^{2}+\lambda^{2}$ is equal to :
Let $P=\begin{bmatrix}1&0&0\\[2pt]3&1&0\\[2pt]9&3&1\end{bmatrix}$ and $Q=[q_{ij}]$ be two $3\times 3$ matrices such that $Q-P^{5}=I_{3}$.
Then $\displaystyle \frac{2q_{11}+q_{31}}{q_{32}}$ is equal to:
Let [$\lambda$] be the greatest integer less than or equal to $\lambda$. The set of all values of $\lambda$ for which the system of linear equations x + y + z = 4, 3x + 2y + 5z = 3, 9x + 4y + (28 + [$\lambda$])z = [$\lambda$] has a solution is :
Let A = $\left[ {\matrix{
1 & 0 & 0 \cr
1 & 1 & 0 \cr
1 & 1 & 1 \cr
} } \right]$ and B = A20. Then the sum of the elements of the first column of B is :
Consider the following system of equations : x + 2y $-$ 3z = a 2x + 6y $-$ 11z = bx $-$ 2y + 7z = c, where a, b and c are real constants. Then the system of equations :
Which of the following matrices can NOT be obtained from the matrix
$\begin{bmatrix}-1 & 2 \\ 1 & -1\end{bmatrix}$
by a single elementary row operation?
If $A$ is a square matrix of order $3$ such that $\det(A) = 3$ and
$\det(\text{adj}(-4,\text{adj}(-3,\text{adj}(3,\text{adj}((2A)^{-1}))))) = 2^m 3^n$,
then $m + 2n$ is equal to:
Let $A$ be a $2 \times 2$ real matrix with entries from $\{0,1\}$ and $|A|\neq 0$.
Consider the following two statements:
(P) If $A \neq I_2$, then $|A| = -1$
(Q) If $|A| = 1$, then $\operatorname{tr}(A) = 2$
where $I_2$ denotes $2 \times 2$ identity matrix and $\operatorname{tr}(A)$ denotes the sum of the diagonal entries of $A$.
Let $\mathrm{A}=\left[\begin{array}{cc}\frac{1}{\sqrt{2}} & -2 \\ 0 & 1\end{array}\right]$ and $\mathrm{P}=\left[\begin{array}{cc}\cos \theta & -\sin \theta \\ \sin \theta & \cos \theta\end{array}\right], \theta>0$. If $\mathrm{B}=\mathrm{PAP}{ }^{\top}, \mathrm{C}=\mathrm{P}^{\top} \mathrm{B}^{10} \mathrm{P}$ and the sum of the diagonal elements of $C$ is $\frac{m}{n}$, where $\operatorname{gcd}(m, n)=1$, then $m+n$ is :
Let
$A=\begin{bmatrix}
2&1&2\\
6&2&11\\
3&3&2
\end{bmatrix}
\quad\text{and}\quad
P=\begin{bmatrix}
1&2&0\\
5&0&2\\
7&1&5
\end{bmatrix}.
$
The sum of the prime factors of $\left|\,P^{-1}AP-2I\,\right|$ is equal to:
Let $\mathbf{A}$ be a $2 \times 2$ matrix with real entries such that
$\mathbf{A}' = \alpha \mathbf{A} + \mathbf{I}$, where $\alpha \in \mathbb{R} - \{-1, 1\}$.
If $\det(\mathbf{A}^2 - \mathbf{A}) = 4$, then the sum of all possible values of $\alpha$ is equal to:
Let $A=\left[\begin{array}{lll}2 & a & 0 \\ 1 & 3 & 1 \\ 0 & 5 & b\end{array}\right]$. If $A^3=4 A^2-A-21 I$, where $I$ is the identity matrix of order $3 \times 3$, then $2 a+3 b$ is equal to
Let a, b, c $ \in $ R be all non-zero and satisfy a3 + b3 + c3 = 2. If the matrix A = $\left( {\matrix{ a & b & c \cr b & c & a \cr c & a & b \cr } } \right)$ satisfies ATA = I, then a value of abc can be :
Let the system of linear equations $x + 2y + z = 2$, $\alpha x + 3y - z = \alpha $, $ - \alpha x + y + 2z = - \alpha $ be inconsistent. Then $\alpha$ is equal to :
Consider the system of linear equations
$x + y + z = 4\mu,\quad x + 2y + 2\lambda z = 10\mu,\quad x + 3y + 4\lambda^2 z = \mu^2 + 15$
where $\lambda, \mu \in \mathbb{R}$.
Which one of the following statements is NOT correct?
If the system of linear equations
$7x + 11y + \alpha z = 13$
$5x + 4y + 7z = \beta$
$175x + 194y + 57z = 361$
has infinitely many solutions, then $\alpha + \beta + 2$ is equal to:
If the system of equations
$x + 2y + 3z = 3$
$4x + 3y - 4z = 4$
$8x + 4y - \lambda z = 9 + \mu$
has infinitely many solutions, then the ordered pair $(\lambda,\mu)$ is equal to:
The number of square matrices of order $5$ with entries from the set $\{0,1\}$, such that the sum of all the elements in each row is $1$ and the sum of all the elements in each column is also $1$, is:
If
\[
\begin{vmatrix}
x+1 & x & x \\
x & x+\lambda & x \\
x & x & x+\lambda^2
\end{vmatrix}
= \dfrac{9}{8}\,(103x+81),
\]
then $\lambda,\ \dfrac{\lambda}{3}$ are the roots of the equation:
Let $\mathrm{A}$ be a square matrix such that $\mathrm{AA}^{\mathrm{T}}=\mathrm{I}$. Then $\frac{1}{2} A\left[\left(A+A^T\right)^2+\left(A-A^T\right)^2\right]$ is equal to
Let $\mathbf{A}=\begin{bmatrix} 1 & \tfrac{1}{51} \\[2pt] 0 & 1 \end{bmatrix}$.
If $\mathbf{B}=\begin{bmatrix} 1 & 2 \\ -1 & -1 \end{bmatrix}\mathbf{A}\begin{bmatrix} -1 & -2 \\ 1 & 1 \end{bmatrix}$,
then the sum of all the elements of the matrix $\displaystyle \sum_{n=1}^{50} \mathbf{B}^n$ is equal to:
Let $R=\left(\begin{array}{ccc}x & 0 & 0 \\ 0 & y & 0 \\ 0 & 0 & z\end{array}\right)$ be a non-zero $3 \times 3$ matrix, where $x \sin \theta=y \sin \left(\theta+\frac{2 \pi}{3}\right)=z \sin \left(\theta+\frac{4 \pi}{3}\right) \neq 0, \theta \in(0,2 \pi)$. For a square matrix $M$, let trace $(M)$ denote the sum of all the diagonal entries of $M$. Then, among the statements:
(I) Trace $(R)=0$
(II) If trace $(\operatorname{adj}(\operatorname{adj}(R))=0$, then $R$ has exactly one non-zero entry.
Let $S_{1}$ and $S_{2}$ be respectively the sets of all $a\in \mathbb{R}\setminus\{0\}$ for which the system of linear equations
$ax+2ay-3az=1$
$(2a+1)x+(2a+3)y+(a+1)z=2$
$(3a+5)x+(a+5)y+(a+2)z=3$
has unique solution and infinitely many solutions. Then
Consider the system of linear equations
$x+y+z=5,\quad x+2y+\lambda^2 z=9,\quad x+3y+\lambda z=\mu,$
where $\lambda,\mu\in\mathbb{R}$. Which of the following statements is NOT correct?
For two $3 \times 3$ matrices $A$ and $B$, let
$A + B = 2B^T$ and $3A + 2B = I_3$,
where $B^T$ is the transpose of $B$ and $I_3$ is $3 \times 3$ identity matrix. Then:
Let
$A=\begin{bmatrix}\dfrac{1}{\sqrt{10}} & \dfrac{3}{\sqrt{10}}\\[4pt]-\dfrac{3}{\sqrt{10}} & \dfrac{1}{\sqrt{10}}\end{bmatrix}$
and
$B=\begin{bmatrix}1 & -i\\[2pt] 0 & 1\end{bmatrix}$, where $i=\sqrt{-1}$.
Let $\mathrm{A}=\left[\begin{array}{cc}\alpha & -1 \\ 6 & \beta\end{array}\right], \alpha>0$, such that $\operatorname{det}(\mathrm{A})=0$ and $\alpha+\beta=1$. If I denotes $2 \times 2$ identity matrix, then the matrix $(I+A)^8$ is :
Let the system of linear equations4x + $\lambda$y + 2z = 0 ,2x $-$ y + z = 0 , $\mu$x + 2y + 3z = 0, $\lambda$, $\mu$$\in$R. has a non-trivial solution. Then which of the following is true?
Consider the following system of equations
\[
\begin{cases}
\alpha x+2y+z=1,\\
2\alpha x+3y+z=1,\\
3x+\alpha y+2z=\beta
\end{cases}
\]
for some $\alpha,\beta\in\mathbb{R}$. Then which of the following is NOT correct?
Let $A$ be a $3\times3$ real matrix such that
\[
A\!\begin{pmatrix}1\\0\\1\end{pmatrix}
=2\!\begin{pmatrix}1\\0\\1\end{pmatrix},\qquad
A\!\begin{pmatrix}-1\\0\\1\end{pmatrix}
=4\!\begin{pmatrix}-1\\0\\1\end{pmatrix},\qquad
A\!\begin{pmatrix}0\\1\\0\end{pmatrix}
=2\!\begin{pmatrix}0\\1\\0\end{pmatrix}.
\]
Then, the system $(A-3I)\!\begin{pmatrix}x\\y\\z\end{pmatrix}=\begin{pmatrix}1\\2\\3\end{pmatrix}$ has:
If $\alpha$ + $\beta$ + $\gamma$ = 2$\pi$, then the system of equations :- x + (cos $\gamma$)y + (cos $beta$)z = 0,(cos $\gamma$)x + y + (cos $\alpha$)z = 0(cos $\beta$)x + (cos $\alpha$)y + z = 0 has :
Let $A$ be a $3 \times 3$ real matrix such that $A^2(A-2 I)-4(A-I)=O$, where $I$ and $O$ are the identity and null matrices, respectively. If $A^5=\alpha A^2+\beta A+\gamma I$, where $\alpha, \beta$, and $\gamma$ are real constants, then $\alpha+\beta+\gamma$ is equal to :
Let $A = [{a_{ij}}]$ be a square matrix of order 3 such that ${a_{ij}} = {2^{j - i}}$, for all i, j = 1, 2, 3. Then, the matrix A2 + A3 + ...... + A10 is equal to :
Let $B=\left[\begin{array}{ll}1 & 3 \\ 1 & 5\end{array}\right]$ and $A$ be a $2 \times 2$ matrix such that $A B^{-1}=A^{-1}$. If $B C B^{-1}=A$ and $C^4+\alpha C^2+\beta I=O$, then $2 \beta-\alpha$ is equal to
Let $A = \left[ {\matrix{ 2 & 3 \cr a & 0 \cr } } \right]$, a$\in$R be written as P + Q where P is a symmetric matrix and Q is skew symmetric matrix. If det(Q) = 9, then the modulus of the sum of all possible values of determinant of P is equal to :
Let $A = [{a_{ij}}]$ be a 3 $\times$ 3 matrix, where ${a_{ij}} = \left\{ {\matrix{ 1 & , & {if\,i = j} \cr { - x} & , & {if\,\left| {i - j} \right| = 1} \cr {2x + 1} & , & {otherwise.} \cr } } \right.$ Let a function f : R $\to$ R be defined as f(x) = det(A). Then the sum of maximum and minimum values of f on R is equal to:
For $x \in \mathbb{R} - \{0,1\}$, let $f_1(x)=\dfrac{1}{x}$, $f_2(x)=1-x$, and $f_3(x)=\dfrac{1}{1-x}$ be three given functions.
If a function $J(x)$ satisfies $(f_2 \circ J \circ f_1)(x)=f_3(x)$, then $J(x)$ is equal to:
Let the system of linear equations
\[
\begin{cases}
x + y + kz = 2,\\
2x + 3y - z = 1,\\
3x + 4y + 2z = k
\end{cases}
\]
have infinitely many solutions. Then the system
\[
\begin{cases}
(k+1)x + (2k-1)y = 7,\\
(2k+1)x + (k+5)y = 10
\end{cases}
\]
has:
Consider the system of linear equations$-$x + y + 2z = 0 3x $-$ ay + 5z = 12x, $-$ 2y $-$ az = 7, Let S1 be the set of all a$\in$R for which the system is inconsistent and S2 be the set of all a$\in$R for which the system has infinitely many solutions. If n(S1) and n(S2) denote the number of elements in S1 and S2 respectively, then
If $A=\begin{bmatrix}\sqrt2&1\\-1&\sqrt2\end{bmatrix}$, $B=\begin{bmatrix}1&0\\1&1\end{bmatrix}$,
$C=ABA^{\mathrm T}$ and $X=A^{\mathrm T}C^{2}A$, then $\det X$ is equal to:
For $\alpha,\beta\in\mathbb{R}$, suppose the system of linear equations
$\begin{aligned}
x-y+z&=5,\\
2x+2y+\alpha z&=8,\\
3x-y+4z&=\beta
\end{aligned}$
has infinitely many solutions. Then $\alpha$ and $\beta$ are the roots of:
Let y = y(x) satisfies the equation ${{dy} \over {dx}} - |A| = 0$, for all x > 0, where $A = \left[ {\matrix{ y & {\sin x} & 1 \cr 0 & { - 1} & 1 \cr 2 & 0 & {{1 \over x}} \cr } } \right]$. If $y(\pi ) = \pi + 2$, then the value of $y\left( {{\pi \over 2}} \right)$ is :
Suppose the vectors x1, x2 and x3 are the solutions of the system of linear equations, Ax = b when the vector b on the right side is equal to b1, b2 and b3 respectively. if${x_1} = \left[ {\matrix{ 1 \cr 1 \cr 1 \cr } } \right]$, ${x_2} = \left[ {\matrix{ 0 \cr 2 \cr 1 \cr } } \right]$, ${x_3} = \left[ {\matrix{ 0 \cr 0 \cr 1 \cr } } \right]$${b_1} = \left[ {\matrix{ 1 \cr 0 \cr 0 \cr } } \right]$, ${b_2} = \left[ {\matrix{ 0 \cr 2 \cr 0 \cr } } \right]$ and ${b_3} = \left[ {\matrix{ 0 \cr 0 \cr 2 \cr } } \right]$, then the determinant of A is equal to :
The value of k $\in$R, for which the following system of linear equations. 3x $-$ y + 4z = 3,x + 2y $-$ 3z = $-$2, 6x + 5y + kz = $-$3,has infinitely many solutions, is :
Let $A$ be a $3 \times 3$ matrix such that $A^{2} - 5A + 7I = 0$.
\textbf{Statement I:}
$A^{-1} = \dfrac{1}{7}(5I - A)$.
\textbf{Statement II:}
The polynomial $A^{3} - 2A^{2} - 3A + I$ can be reduced to $5(A - 4I)$.
Then:
If
$A=\begin{bmatrix}
e^{t} & e^{-t}\cos t & e^{-t}\sin t\\[4pt]
e^{t} & -e^{-t}\cos t - e^{-t}\sin t & -e^{-t}\sin t + e^{-t}\cos t\\[4pt]
e^{t} & 2e^{-t}\sin t & -2e^{-t}\cos t
\end{bmatrix}$,
then $A$ is:
The values of $\lambda$ and $\mu$ such that the system of equations $x + y + z = 6$, $3x + 5y + 5z = 26$, $x + 2y + \lambda z = \mu $ has no solution, are :
Let A = [aij] be a real matrix of order 3 $\times$ 3, such that ai1 + ai2 + ai3 = 1, for i = 1, 2, 3. Then, the sum of all the entries of the matrix A3 is equal to :
$ \textbf{Q:}$ For the system of linear equations $x + y + z = 6,\ \alpha x + \beta y + 7z = 3,\ x + 2y + 3z = 14$, which of the following is **NOT true**?
For a $3\times3$ matrix $M$, let $\operatorname{trace}(M)$ denote the sum of all the diagonal elements of $M$. Let $A$ be a $3\times3$ matrix such that $|A|=\dfrac{1}{2}$ and $\operatorname{trace}(A)=3$. If $B=\operatorname{adj}(\operatorname{adj}(2A))$, then the value of $|B|+\operatorname{trace}(B)$ equals:
Let $\alpha \in (0,\infty)$ and
$A=\begin{bmatrix}1 & 2 & \alpha \\ 1 & 0 & 1 \\ 0 & 1 & 2\end{bmatrix}$.
If $\det(\operatorname{adj}(2A-A^T)\cdot\operatorname{adj}(A-2A^T))=2^8$,
then $(\det(A))^2$ is equal to:
If $B = \left[ {\matrix{
5 & {2\alpha } & 1 \cr
0 & 2 & 1 \cr
\alpha & 3 & { - 1} \cr
} } \right]$ is the inverse of a 3 × 3 matrix A, then the sum of all values of $\alpha $ for which
det(A) + 1 = 0, is :
If $A=\begin{bmatrix}
1 & 2 & 2\\
2 & 1 & -2\\
a & 2 & b
\end{bmatrix}$ is a matrix satisfying the equation $AA^{T}=9I$, where $I$ is $3\times 3$ identity matrix, then the ordered pair $(a,b)$ is equal to :
If the system of linear equations x + y + 3z = 0 x + 3y + k2z = 0 3x + y + 3z = 0 has a non-zero solution (x, y, z) for some k $ \in $ R,then x + $\left( {{y \over z}} \right)$ is equal to :
If A is a symmetric matrix and B is a skew-symmetric matrix such that A + B = $\left[ {\matrix{
2 & 3 \cr
5 & { - 1} \cr
} } \right]$, then AB is equal
to :
If the system of equations
$(\lambda-1)x+(\lambda-4)y+\lambda z=5$
$\lambda x+(\lambda-1)y+(\lambda-4)z=7$
$(\lambda+1)x+(\lambda+2)y-(\lambda+2)z=9$
has infinitely many solutions, then $\lambda^2+\lambda$ is equal to: